Current Zoology, 2017, 63(6), 607–613 doi: 10.1093/cz/zow112 Advance Access Publication Date: 25 December 2016 Article Article Loss of largest and oldest individuals of the Montpellier snake correlates with recent warming in the southeastern Iberian Peninsula a, b b Cosme LOPEZ -CALDERON *, Monica FERICHE , Esmeralda ALAMINOS , and b Juan M. PLEGUEZUELOS aDepartment of Zoology, Faculty of Biology, University of Seville, C/Reina Mercedes, Seville, E-41012, Spain and bDepartment of Zoology, Faculty of Sciences, University of Granada, Granada, E-18071, Spain *Address correspondence to Cosme Lopez-Calder on. E-mail: [email protected]. Received on 26 July 2016; accepted on 14 November 2016 Abstract The effects of climate change on organisms are now being extensively studied in many different taxa. However, the variation in body size, usually shrinkage in response to increasing temperature, has received little attention regarding to reptiles. During past periods of global warming, many or- ganisms shrank in size, and current evidence and experiments manipulating temperature have shown a biomass decrease in some organisms with increasing temperatures. Here we test whether the body size of the Montpellier snake Malpolon monspessulanus from the southeastern Iberian Peninsula is changing and correlated with the increasing temperature in this region during a 39- year period (1976–2014). We measured the snout–vent length (SVL) of vouchers in scientific collec- tions to check for trends in adult body size at the population level in relation with temperature, while controlling for the age of the individuals (estimated by skeletochronology, n ¼141). Given the great ontogenetic variation in body size of the study species, we categorized age in 3 classes: “young adults” (under 5 years old), “intermediate adults” (from 5 to 7 years old), and “old adults” (from 8 to 14 years old). By means of linear mixed models, we found a negative relationship be- tween SVL of “old adults” and average annual temperature in the region during the lifetime of each individual. Our results indicate that largest and oldest individuals of the Montpellier Snake, that is, males because of strong sexual size dimorphism in this species, disappeared from the study population, and suggest that it occurred in response to rising environmental temperature. Key words: body shrinkage, climate warming, differential mortality, Malpolon monspessulanus, skeletochronology, snakes, Spain. Our planet has always been changing and, therefore, varying its bio- meteorological events (IPCC 2007). In this scenario, the study of the diversity (Smith et al. 2012). The problem of the recent climate effects of climate change on organisms is now being extensively change led by human activities lies in its intensity and speed, as the studied in different taxa. These effects can be classified as: (1) shifts global average surface temperature has increased 0.74 6 0.18 C in the distribution range, (2) local plasticity or adaptation through during the period 1906–2005 (IPCC 2007), mostly during the last phenotypical and/or phenological changes to remain in the place of 50 years (0.13 6 0.03 C per decade). The forecast expects an in- origin, and finally (3) extinction on a local or larger scale (Millien crease of the global average surface temperature for the decade et al. 2006). Most studies in this field deal with range shifts and 2090–2099 relative to the period 1980–1999 of 1.8 C (1.1–2.9 C) phenological changes in organisms (Walther et al. 2002; Parmesan in the best possible scenario (B1), whereas 4.0 C (2.4–6.4 C) in the 2006), with body-size variation being one of the responses that has worst (A1F1), as well as an intensification of the extreme received the least attention (review in Gardner et al. 2011). During VC The Author (2016). Published by Oxford University Press. 607 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact [email protected] 608 Current Zoology, 2017, Vol. 63, No. 6 past periods of global warming, marine and terrestrial organisms (July) ¼ 25.36 2.4 C, annual average ¼ 16.4 6 1.7 C, and yearly shrank in size (Smith et al. 2009), and experiments manipulating rainfall ¼ 412.1 6 226.7 mm (data from 98 meteorological stations temperature have shown a decline in the size or biomass of some or- for the 1980–2004 period, summarized in Moreno-Rueda et al. ganisms with rising temperature; for example, in phytoplankton 2009). The vegetation consists of evergreen oak Quercus rotundifolia, (Sommer et al. 2007), fish (Desai and Singh 2009), and beetles scrubs, and some species of pines Pinus spp., mixed with cultivated (Stillwell and Fox 2009). Body size is the most evident morphologic areas of cereals and orchards in the foothills, plains, and valleys. trait of a given organism, it is easy to quantify, and large sample The snake under study was selected for the amount of data avail- sizes can be obtained with little effort. In addition, many life-history able, as it is the commonest snake of the Iberian Peninsula. This spe- traits depend on this parameter: clutch (or litter) size and weight, cies has the widest diet and furthermore is considered the second brood time or gestation time, water and energy requirements, meta- more generalist snake in habitat use in the study region (Segura et al. bolic rate, position in the trophic chain, maturation time, intrinsic 2007). Within our data set, the study species spread 3-1850 m asl, rate of population growth, lifespan, and extinction risk, among with a mean elevation value of 781.2 m (SD ¼ 367.7). Specimens others (Blueweiss et al. 1978; Millien et al. 2006; Meiri 2008; came from field sampling conducted from 1979 to 2014, within the Gardner et al. 2011). framework of several studies (i.e., Feriche et al. 2008). During most Within the animal kingdom, the most widely studied groups for of the years, we sampled 2–4 days per month (daily searches lasted body-size shrinkage in response to climate change have been the 4 h), throughout all months of the year. Specimens were collected endothermic ones, whereas the terrestrial ectotherms have received among those killed by traffic or local people. Afterwards, individ- little attention (reviews in Gardner et al. 2011; Sheridan and uals were preserved in ethanol at the collection of the University of Bickford 2011). For instance, body shrinkage was correlated to re- Granada, Spain. The review of scientific collections has been pro- cent warming in Bufo bufo females from the UK over a 22-year posed as an important tool to understand the effect of climate period (Reading 2007); and also, body shrinkage at the population change on body sizes (Millien et al. 2006). level correlated to recent warming in 6 species of plethodontid sala- To check for snake body-size variation during the study period, manders from the USA during a 55-year period (Caruso et al. 2014). we used the snout–vent length (SVL) of specimens, measured by a However, no proof of this trend is available in the literature for rep- cord along the middorsal line, and afterwards by a flexometer (in- tiles. The opposite reaction, increasing body size related to climate strumental error ¼ 61 mm). The measurement error of snake’s SVL warming, has been detected in a few cases, generally restricted to or- has been quantified as being approximately 1% of the body size ganisms of high latitudes or elevations, as in the lizard Zootoca (Blouin-Demers 2003); therefore, it is possible to detect shrinkage if vivipara in France (Chamaille´-Jammes et al. 2006). Particularly this is greater than the error value. Reptile vouchers from scientific within snakes, there are few studies on responses to climate change collections and especially snakes, shrink due to the fixative and pre- (Weatherhead and Madsen 2009), and to our concern, none avail- servative, and measurements of fresh specimens are not directly able on body-size shift as a response to gradual long-term increase in comparable to measurements of preserved ones (Barry 2011). As not environmental temperature. all the vouchers in collection were measured for body size when However, snakes can be model organisms in analyzing body-size fresh, we needed to estimate this value from some specimens. We re- shifts in response to climate change, as they have no limbs and most gressed fresh (SVL1) against preserved (SVL2) body size from a sub- of the growth is expressed in the longitudinal axis (at least when set of individuals that offered both measurements (n ¼ 62), assuming compared with limbed ectotherms). In addition, the Mediterranean the shrinking process is not continuous, but rather stops after the Basin has been proposed as one of the 2 most responsive regions to first days of preservation in alcohol (Shields and Carlson 1996). climate change in the world (Giorgi 2006). Furthermore, the Iberian This has been tested for green iguanas Iguana iguana, finding that Peninsula is one of the European regions where the effects of global shrinking stops after 30 days in preservative (Vervust et al. 2009). warming to herptiles will be the most dramatic (Araujo et al. 2006; For estimating the age of snake vouchers, we used a skeletochro- Carvalho et al. 2010). Specifically for the southeastern Iberian nology approach. This was based on the dense lines in bones of ecto- Peninsula, a temperature increase of 0.07 C per year has been previ- therms from temperate regions, which corresponded to active ously proved (for the 1983–2004 period; Moreno-Rueda et al.